Method of refining mineral oils



A Dec. .13, 1938. E TERRES ET AL 2,140,485

METHOD'OF REFINING MINERAL OILS Filed May 22, 1955 ms ,7a/nder Patented Dec. 13., 1938 UNITED STATES PATENT OFFICE METHOD F REFINING MINEBALOILS Ernest Terres, New York, Erich Saegebarth, 'Long Island City, N. Y., and Joseph Moos, Berlin-Marlendorf, and Hans Ramser, Berlin- Steglitz, Germany, assignors, by mesne assignments, to Edeleanu Gesellschaft, m. b. H., Berlin, Germany, a corporation o! Germany Application May 22, 1935, Serial No. 22,914

8 Claims. ((1196-13) This invention aims to provide an improved method of refining mineral oils. More particularly, the invention relates to the use of dichlorodiiluoromethane as a solvent for treating lubricating oil `stocks to produce high quality lubricating oils to meet the needs of modern automobile and airplane motors, although the invention is not limited thereto.

For these uses,- lubricating oil stocks require *lo treatment to improve the viscosity and stability ber 31, 1931, Patent No. 2,009,454, Adated July 30, 4..

We have discovered that liquid dichlorodmuoromethane can be used very successfully as a de- 25 asphaltizing solvent, and that it can also be used to effect a phase separation of hydrocarbon oils at elevated temperatures below -its critical temperature (232.6 FJ. j f

The extraction or removal of aromatic and un- 30 saturated hydrocarbons can be effected very advantageously by employing dichlordifluoromethane in conjunction with other solvents, as will be described hereafter, and -such use isl `part of our invention. i

According to our invention, therefore, dichlorodifiuoromethane may be employed effectively'to accomplish deasphaltizing, dewaxing, .and ksepa.-

rationl or removal of aromatic and hydrocarbons. 40 The use of dichlorodifluoromethane for-'refin-` phaltenes are insoluble at all temperatures and separate out as a separate layer from a solution of oil and the solvent. By avoiding low temperatures, there will be no separation of wax; and by 55 avoiding elevated temperatures above a, critical methane at normal temperatures, whereas aspointdeterminable for each stock treated there will be no separation into layers vof hydrocarbons normally wholly miscible in the solvent. Thus the asphaltenes can be removed without at the same time causing separation of other components.

In the accompanying drawings, wherein we have shown several embodiments of the invention for purposes of illustration,

Fig. 1 is a flow diagram lshowing the use of dichlorodiiluoromethane in the successive treatment of an asphaltic waxy oil stock for asphalt removal', wax removal, and separation of the oil into arafllnate fraction and an extract fraction by means of a selective solvent;

Fig. 2 is a flow diagram showing the use of dichlorodiiluoromethane for dividing an asphaltfree oil into a lighter oil fraction and a heavier oil fraction.

l It will be evident to persons skilled in the art that the method steps shown in these ilow dlaa grams may be combined in various different ways and in various diierent sequences. l

' The following examples illustrate various types of treatment. i

Example 1 This example illustrates the use of the solvent for deasphaltizing.

A Mid-Continent residual oil having an A. P. I. gravity of 20. Saybolt viscoslties of 997 at 130 F.

' and 145 at 210 F., a Conradson carbon residue of 5.6, land a wax content of by volume, was agitated at 130 F. with four volumes of dichlorodifluoromethane in a vessel under pressure sutilcient to' maintain the solvent in liquid phase. Upon allowing the mixture to stand,'two layers were formed.Y 'Ihe upper layer consisted of as- Dhalte'nes containing", some of the solvent in solu- `"tion, while the'lower layer consisted of the bulk ofthe solvent containin the oil in solution. n The ing waxy asphaltic lubricating oil stocks is reng dered particularly valuable by the fact that, if

layers or phases were separated and the solvent Vremoved'-thexefi'om.

The-yield of asphalt was 13% by volume and the yield of-'oil was 87% by volume. The deasphaltized oil had an A. P. I. gravity of 21.9, Saybolt viscosities of 664 at 130 F. and 109 at 210 F., and a carbon residue value of 3.0.

As previously indicated, dichlorodiuorometh- .ane is suitable for dewaxing. When highly asphaltic stocks are to be dewaxed, the stock will Hordinarily be deasphaltized iirst in order to facilitate the mechanical removal of the wax following Aprecipitation thereof, as by filtering, and to permit securing the asphaltenes and wax separated from each othen tenes, the separation of asphaltenes and wax may be. carried out in one operation by dissolving the stock in the solvent, chilling the mixture to the dewaxing temperature, and filtering. In this case the asphaltenes will be separated with the Wax.

Example 2 This example illustrates the use of dichlorodiuoromethane for dewaxin'g.

A mixed-base lubricating oil of Mid-Continent origin with a pour point of 110 F. was mixed with 2.5 volumes of liquid dichlorodifluoromethane in a pressure vessel. to 19 F. by applying suction to the vessel to cause evaporation of the solvent, the amount evaporated being replaced by introducing liquid solvent into the vessel, keeping the amount of liquid in the vessel constant. The chilled mixture was then filtered through an ordinary type iilter press at 19 F., under a pressure of about 2 lbs. per sq. in. The iiltered oil was freed of solvent by evaporation. v

The properties of the oil before and after dewaxing were as follows:

Before After dewaxing dewaxing A. .I 24.4 `r3.1 Viscosity at 210 F 61 `05 Viscosity gravity constant- 0. 843 0. 852 Pour point, F 0 5 Dichloro'difluoromethane possesses a negative temperature coeillcient in regard to the solubility of mineral oils therein. Upon heating a solution of asphalt-free oil in the solvent, a point can be reached at which separation into two liquid layers or phases, containing oil of differing properties, occurs. One of the two phases contains the bulk amount 'of the solvent, having a certain amount of o il in solution, the amount of oil being smaller the higher the temperature. kThis oil will be lighter than the original oil. The other phase contains the oil which has separated out from the main body of solvent and' is saturated with the solvent, and the oil in this phase is heavier than the original oil. Such phase separation will occur at about 212 F. in the case of a heavy cylinder stock. The specific gravity of the solvent, which is 1.5 at -.36 F.,

vdecreases to 0.83 at 225 F. Theposition of the two layers may therefore be reversed upon .passing a certain temperature, dependent upon the specific gravity of the oil.

Example 3 maintain the solvent in" liquid phase. Upon` 'standing at this temperature, two layers were formed. The upper layer comprised the bulk of the solvent, and contained the fraction of oil which remained dissolved therein. The lower layer consisted of the oil which was undisrwilvedl 'I'he solution was cooled Dissolved Undisoil solved oil 10. 6 89. 4 27. 3 23. 6 Viscosity at 130 F 1790 Viscosity at 210 F 255 Carbon residue 1. 2 4. l

Dichlorodiuoromethane is not entirely miscible with selective solvents such as quinoline, aniline, cresol, phenol, chlorophenol, and others, used for extracting aromatic and unsaturated hydrocarbons and which are characterized by having a selective action as between high and low viscosity-index hydrocarbons. That is, when mixed with such solvents a phase separation will occur. It is therefore possible to use dichlorodifluoromethane in conjunction with these solvents in the way that liquid propane is used, to eiect double solvent rening. 'I'his procedure is especially advantageous for the treatment of residual oils. which are hard to refine, and is likewise applicable to distillates, as shown by the following examples.

Example 4 One volume of a Mid-Continent residual cyliner stock was agitated with four volumes of dichlorodiiiuoromethane and one volume of phenol, at 104 F. Upon standing, two layers were formed and these were separated. 'I'he raiiinate layer, without removal of solvents contained therein. was mixed again with one volume of phenol at 104 F., and upon standing two layers again formed. The solvent was removed from the resulting ramnate layer, and from the two extract phases. The properties of the original stock and of the ilnal ramnate are shown in the table of the next example.

Example 5 One volume of the same Mid-Continent stock referred to in the preceding. example was agitated and heated to 140 F,l in admixture with four volumes of dichlorodiuoromethane and one volume of parachlorophenoL Upon layer sepa- `ration, the rafiinate layer was treated in the same manner with one volume of parachlorophenol at y140 F., again resulting in a separation into a raiiinate layer andan extract layer upon standing. The final ramnate,` afterA solvent removal, had the properties shown'` in the followingv table:

Original Ralnate Ramnate oil Examplei Example 5 Yield volume, percent l 100 66 54 A. P. I 20 24. 5 27. 5 Viscosity at 130 F 997 524 320 Viscosity at 210 F 145 98 77 Carbon residue 5. 6 0. 67

Example 6 A dewaxed Mid-Continent distillate was mixed and agitated with 3 volumes of dichlorodiuoromethane and 1 volume 4of aniline, at 104 F. The

layers were allowed to separate andA were freed of solvents. The raffinate (refined oil) was contacted with 10% of diatomaceous earth or other color adsorbing material at 450 F. The properties of the untreated oil and of the finished raffinate are shown in the tabl'e of the next.

example.

Example 7 Untreatcd Rnllinate Railinntc stock Example 6 Example 7 Yield volume, percent. 100 90 70 A. I. I 23. 2 24.9 27.5 1287 l054 735 Viscosity at 210? F Jl 84. 5 74.8 Viscosity index 75 84 94 Carbon residue A. 1. 9 l. l 0. 42

Eample 8 One volume of the same Mid-Continent distillate, referred to in Examples 6 and '7, was mixed and agitated with two volumes of dichlorodiuoromethane and three.volumes of quinoline. The mixture was cooled and at +10 F. a separation into two layers commenced. Cooling was continued to -22 F. to increase the rate of settling out ofthe layers. After equilibrium was reached the two layers were separatedand the solvents removed therefrom. The raftinate oil, which amounted to 68 vol. of the untreated oil, was finished by contacting with. 10% of clay at 450 F. The character of the finished raffinate is shown in the following table:

. Untreated Finished oil raffinate A. P. I 23. 2 28. 0 Viscosity at 100 'F 1287 728 Viscosity at 210 F 91 74. 6 Viscosity indexm. 75 94 Carbon residue l. 9 0.30 A. S. T. M. color 5 accordance with Vour invention liquid dichlorodifluoromethanemay be used for deasphaltizin'g, dewaxing, and is of `use in extraction or removal of' types of hydrocarbon constituents,` such as aromatic,'unsaturated and unstable components. fWhen oil is dissolved in dichlorodiuoromethane it may then be deasphaltized and dewaxed by appropriate -adjustment of temperature; and may be refined by adjusting the temperature to cause a phase separation, or by extracting the solution with phase-forming selective solvents. 'I'hus the presence of the dichlorodifluoromethane is effective in all stages of a complete refining process. i

Attention is called to our copending companion application Ser. No. 23,130, filed May 23, 1935, which relates to the use of the broad group of organic iiuorine compounds, the use of only one species of which (dichlorodiluoromethane) is expressly described and claimed herein.

What we claim is as follows:

1. A method of refining an asphaltic mineral oil comprising dissolving the oil in dichlorodifluoromethane, removing the undissolved asphalt from the solution at a temperature at which other components of the oil remain dissolved, and extracting the solution with a selective solvent in which the dichlorodifiuoromethane is not wholly miscible at a. temperature'below the critical pointv of the original solution of oil in dichlorodifluoromethane, to produce an extract phase and a raf'- nate phase, and separating the two phases.

2. The method of refining an asphaltic waxy mineral oil comprising dissolving the oil in dichlorodifluoromethane, removing the undissolved asphalt at a temperature at which the other components of the oil remain dissolved, chilling the mixture to a low temperature at which the wax separates out, removing the separated wax, and extracting the solution with a selective solvent in which the dichlorodiuoromethane is not wholly miscible at a temperature below the critical point of the original solution of oil in dichlorodifiuoromethane, to produce an extract phase and a raffinate phase, and separating the two phases.

3. A method of treating a mineral oil comprising dissolving the oil in dichlorodiiiuoromethane and heating to a temperature above wthe critical point of' the solution and below 232.6o F. to cause a separating out of initially dissolved components of the oil and the lformation of two layers, and dividing out the layers,

4. A method of treating an asphalt-free mineral oil comprising dissolving the oil in dichlorodiiiuoromethane and heating A'the solution to a temperature above the critical point thereof and below 232.6 F. to produce two liquid phases, and separating the phases to obtain a relative lighter oilfraction and a relatively heavier oil fraction.

5. A method of treating a mineral oil comprising dissolving the oil in dichlorodiiiuoromethane and thereafter extracting at a temperature in excess of 100 F. and less than 232.6" F. with a selective solvent which has selective action as between high and low viscosity-index hydrocarbons and in which the dichlorodifluoromethane is not wholly miscible, to produce two lliquid phases, and separating the two phases.

6. A method of refining a substantially waxfree mineral oil comprising dissolving the oil in dichlorodiluoromethane and extracting at a tempcrature above 100 F. and not above 232.6 F. with a selective solvent which has aselective action as between high andlow viscosity-index hydrocarbons and in which the dichlorodifluoromethane is not wholly miscible, to produce two liquid phases, and separating the two phases.

7. A method of treating mineral oil comprising dissolving the oil in dichlorodifluoromethane and thereafter extracting at a temperature below 232.6's F. at which contained wax is substantially dissolved with a selective solvent in which the dichlorodifluoromethane is not'wholly miscible, to produce an extract phase and a raffinate phase, and separating the two phases.

8. A method of refining an asphaltic mineral oil comprising dissolving the oil in dichlorodiiluoromethane at a temperature above 100 F. and not above the critical point of the solution to dissolve all except asphaltic components, removingdriving oi! the latter to produceva lubricating oil the undissolved residue, heating the solution to fraction having a. high viscosity index.

a temperature above its critical point and below ERNEST TERRES. 232.6 F. to cause separation thereof into two ERICHVSAEGEBAR'I'H.` layers, dividing out the layer containing the com- JOSEPH MOOS.

nnnents dissolved in dichlorodiuoromethane and HANS RAMSER. 

